1. Field of the Invention
This invention relates to a novel electric current producing cell. More particularly, this invention relates to improvements in electric current producing cells having alkali metal-containing anodes, electrolytes and cathodes, wherein the electrolytes are solid materials. The present invention is more specifically directed to electric current-producing cells having alkali metal-containing anodes, solid electrolytes and cathodes containing one or more chalcogenides as the cathode-active material.
2. Description of the Prior Art
There has been considerable interest in recent years in developing high energy density batteries or voltaic cells. Among the systems being investigated are those employing nonaqueous liquid, fused or solid electrolytes, with lightweight metals, such as alkali metals, as anodes, and with cathodes containing metal chalcogenide compounds. Such systems are described, for example, in U.S. Pat. Nos. 3,988,164; 3,925,098; 3,864,167 and 3,791,867.
Various efforts have been made to develop new solid state electrolytes for secondary cell systems. Alkali metal-aluminum-chlorine and alkali metal-aluminum-bromine compounds have been utilized in liquid and molten state electrolyte systems (e.g., as described in U.S. Pat. Nos. 3,877,984 and 3,751,298) and solid alkali-metal-aluminum-halogen compound electrical conductivity studies have been made. Recently issued U.S. Pat. No. 4,066,824 to Rao et al. describes electrochemical cells having alkali metal anodes, metal chalcogenide cathodes, and solid electrolytes, these electrolytes being essentially one or more solid alkali metal aluminum tetrahalide compounds.
U.S. Pat. No. 4,115,633 describes cells with AB.sub.x C.sub.y solid electrolytes wherein A is a metallic atom with an atomic number no greater than 55, B is a group IIIA metallic atom, C is a group IVA atom, and x and y are such that the compound is essentially electrically neutral. This reference does not teach the use of boron as a B-type atom, nor does it specifically teach the use of aluminum as a B-type atom, albeit aluminum is encompassed generically. The patent suggest gallium and indium as effective B-type atoms and nowhere shows examples or states specific use of any other B-type atoms. Further, the cathodes described therein are elemental or otherwise non-chalcogenide. Hellstrom et al., Electrochemical Society, Extended Abst., Vol. 78-1, pp. 393-5 (1978) describe the compounds LiAlS.sub.2, NaAl.sub.2, KAlS.sub.2, Na.sub.2 S.(9-11)Al.sub.2 S.sub.3, K.sub.2 S.(9-11)Al.sub.2 S.sub.3 and LiAl.sub.5 S.sub.8 and some ionic conductivity measurements, but nowwhere suggest battery utility, much less batteries with chalcogenide cathodes. In summary, to date there has been no suggestion that the alkali metal-metal-chalcogen compounds used in the present invention might be useful in solid state electrolyte systems having alkali metal anodes and chalcogenide cathodes.